1. Prepare an ice-water bath; set aside. Bring a medium saucepan of water to a boil over medium-high heat; add salt. Add beans; simmer until just tender, 5 to 6 minutes. Plunge beans into ice-water bath to stop the cooking; let cool completely in water. Drain.

2. Toss together green beans, fennel, onion, olives, feta, oil, vinegar, and 1/4 teaspoon salt in a medium bowl; season with pepper. Let stand at room temperature 15 minutes.

3. Preheat broiler. Place bread on a baking sheet. Broil, turning once, until bread darkens, about 3 minutes per side. Cut bread into 1-inch cubes; add to salad, and toss to combine.